Transmitting channel state information reference signals in new radio

ABSTRACT

Certain aspects of the present disclosure provide techniques for transmitting and processing channel state information (CSI) reference signals (CSI-RS). An exemplary method includes determining a configuration of channel state information reference signals (CSI-RSs), wherein the configuration indicates a set of resource elements (REs) to be used for CSI-RSs and a first mapping of CSI-RS ports to the set of REs; sending an indication of the configuration of the CSI-RSs; and transmitting the CSI-RSs according to the determined configuration.

CROSS-REFERENCE TO RELATED APPLICATION

The present Application for Patent is a national stage application under35 U.S.C. 371 of PCT/CN2017/114342, filed Dec. 2, 2017, which claimspriority to International Application No. PCT/CN2016/108346, filed Dec.2, 2016, which are both assigned to the assignee of the presentapplication and expressly incorporated by reference in their entireties.

INTRODUCTION

Aspects of the present disclosure related generally to wirelesscommunications systems, and more particularly, to transmitting channelstate information (CSI) reference signals (CSI-RSs) in a new radio (NR)wireless network.

Wireless communication systems are widely deployed to provide varioustelecommunication services such as telephony, video, data, messaging,and broadcasts. Typical wireless communication systems may employmultiple-access technologies capable of supporting communication withmultiple users by sharing available system resources (e.g., bandwidth,transmit power). Examples of such multiple-access technologies includeLong Term Evolution (LTE) systems, code division multiple access (CDMA)systems, time division multiple access (TDMA) systems, frequencydivision multiple access (FDMA) systems, orthogonal frequency divisionmultiple access (OFDMA) systems, single-carrier frequency divisionmultiple access (SC-FDMA) systems, and time division synchronous codedivision multiple access (TD-SCDMA) systems.

A wireless communication network may include a number of Node Bs thatcan support communication for a number of user equipments (UEs). A UEmay communicate with a Node B via the downlink and uplink. The downlink(or forward link) refers to the communication link from the Node B tothe UE, and the uplink (or reverse link) refers to the communicationlink from the UE to the Node B.

These multiple access technologies have been adopted in varioustelecommunication standards to provide a common protocol that enablesdifferent wireless devices to communicate on a municipal, national,regional, and even global level. An example of an emergingtelecommunication standard is new radio (NR, e.g., 5G radio access). NRis a set of enhancements to the LTE mobile standard promulgated by ThirdGeneration Partnership Project (3GPP). It is designed to better supportmobile broadband Internet access by improving spectral efficiency, lowercosts, improve services, make use of new spectrum, and better integratewith other open standards using OFDMA with a cyclic prefix (CP) on thedownlink (DL) and on the uplink (UL) as well as support beamforming,multiple-input multiple-output (MIMO) antenna technology, and carrieraggregation. However, as the demand for mobile broadband accesscontinues to increase, there exists a need for further improvements inNR technology. Preferably, these improvements should be applicable toother multi-access technologies and the telecommunication standards thatemploy these technologies.

SUMMARY

The systems, methods, and devices of the disclosure each have severalaspects, no single one of which is solely responsible for its desirableattributes. Without limiting the scope of this disclosure as expressedby the claims which follow, some features will now be discussed briefly.After considering this discussion, and particularly after reading thesection entitled “Detailed Description” one will understand how thefeatures of this disclosure provide advantages that include improvedcommunications between access points and stations in a wireless network.

Aspects of the present disclosure provide a method for wirelesscommunications. The method generally includes determining aconfiguration of channel state information reference signals (CSI-RSs),wherein the configuration indicates a set of resource elements (REs) tobe used for CSI-RSs and a first mapping of CSI-RS ports to the set ofREs, sending an indication of the configuration of the CSI-RSs, andtransmitting the CSI-RSs according to the determined configuration.

Aspects of the present disclosure provide a method for wirelesscommunications by a receiver. The method generally includes receiving anindication of a configuration of channel state information referencesignals (CSI-RSs) from a transmission reception point (TRP), wherein theconfiguration indicates a set of resource elements (REs) to be used forCSI-RSs and a first mapping of CSI-RS ports to the set of REs,processing CSI-RSs according to the configuration to determine channelstate information, and reporting the channel state information to theTRP.

Aspects of the present disclosure provide an apparatus for wirelesscommunications. The apparatus generally includes means for determining aconfiguration of channel state information reference signals (CSI-RSs),wherein the configuration indicates a set of resource elements (REs) tobe used for CSI-RSs and a first mapping of CSI-RS ports to the set ofREs, means for sending an indication of the configuration of theCSI-RSs, and means for transmitting the CSI-RSs according to thedetermined configuration.

Aspects of the present disclosure provide an apparatus for wirelesscommunications. The apparatus generally includes means for receiving anindication of a configuration of channel state information referencesignals (CSI-RSs) from a transmission reception point (TRP), wherein theconfiguration indicates a set of resource elements (REs) to be used forCSI-RSs and a first mapping of CSI-RS ports to the set of REs, means forprocessing CSI-RSs according to the configuration to determine channelstate information, and means for reporting the channel state informationto the TRP.

Aspects of the present disclosure provide an apparatus for wirelesscommunications. The apparatus generally includes a processor configuredto determine a configuration of channel state information referencesignals (CSI-RSs), wherein the configuration indicates a set of resourceelements (REs) to be used for CSI-RSs and a first mapping of CSI-RSports to the set of REs, to send an indication of the configuration ofthe CSI-RSs, and to transmit the CSI-RSs according to the determinedconfiguration, and a memory coupled with the processor.

Aspects of the present disclosure provide an apparatus for wirelesscommunications. The apparatus generally includes a processor configuredto receive an indication of a configuration of channel state informationreference signals (CSI-RSs) from a transmission reception point (TRP),wherein the configuration indicates a set of resource elements (REs) tobe used for CSI-RSs and a first mapping of CSI-RS ports to the set ofREs, to process CSI-RSs according to the configuration to determinechannel state information, and to report the channel state informationto the TRP, and a memory coupled with the processor.

To the accomplishment of the foregoing and related ends, the one or moreaspects comprise the features hereinafter fully described andparticularly pointed out in the claims. The following description andthe annexed drawings set forth in detail certain illustrative featuresof the one or more aspects. These features are indicative, however, ofbut a few of the various ways in which the principles of various aspectsmay be employed, and this description is intended to include all suchaspects and their equivalents.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above-recited features of the presentdisclosure can be understood in detail, a more particular description,briefly summarized above, may be had by reference to aspects, some ofwhich are illustrated in the appended drawings. It is to be noted,however, that the appended drawings illustrate only certain typicalaspects of this disclosure and are therefore not to be consideredlimiting of its scope, for the description may admit to other equallyeffective aspects.

FIG. 1 is a block diagram conceptually illustrating an exampletelecommunications system, according to aspects of the presentdisclosure.

FIG. 2 is a block diagram conceptually illustrating an example downlinkframe structure in a telecommunications system, according to aspects ofthe present disclosure.

FIG. 3 is a diagram illustrating an example uplink frame structure in atelecommunications system, according to aspects of the presentdisclosure.

FIG. 4 is a block diagram conceptually illustrating a design of anexample Node B and user equipment (UE), according to aspects of thepresent disclosure.

FIG. 5 is a diagram illustrating an example radio protocol architecturefor the user and control planes, according to aspects of the presentdisclosure.

FIG. 6 illustrates an exemplary transmission timeline, according toaspects of the present disclosure.

FIG. 7 illustrates an exemplary resource block structure, according toaspects of the present disclosure.

FIG. 8 illustrates example operations for wireless communications by abase station TRP, according to aspects of the present disclosure.

FIG. 9 illustrates example operations for wireless communications by awireless node, according to aspects of the present disclosure.

FIG. 10 illustrates an example of transmitting reference symbols,according to aspects of the present disclosure.

FIGS. 11A & 11B illustrate examples of transmitting reference symbols,according to aspects of the present disclosure.

FIGS. 12A & 12B illustrate examples of transmitting reference symbols,according to aspects of the present disclosure.

FIGS. 13A & 13B illustrate examples of transmitting reference symbols,according to aspects of the present disclosure.

FIG. 14 illustrates an example of transmitting reference symbols,according to aspects of the present disclosure.

FIG. 15A illustrates an example of CSI-RS location in a self-containedslot, according to aspects of the present disclosure.

FIG. 15B illustrates examples of using time-division orthogonal covercodes with reference symbols, according to aspects of the presentdisclosure.

To facilitate understanding, identical reference numerals have beenused, where possible, to designate identical elements that are common tothe figures. It is contemplated that elements disclosed in one aspectmay be beneficially utilized on other aspects without specificrecitation.

DETAILED DESCRIPTION

Aspects of the present disclosure provide apparatus, methods, processingsystems, and computer program products for new radio (NR) (new radioaccess technology) cell measurement. New radio (NR) may refer to radiosconfigured to operate according to a new air interface (e.g., other thanOrthogonal Frequency Divisional Multiple Access (OFDMA)-based airinterfaces) or fixed transport layer (e.g., other than Internet Protocol(IP)). NR may include Enhanced mobile broadband (eMBB) targeting widebandwidth (e.g. 80 MHz beyond), millimeter wave (mmW) targeting highcarrier frequency (e.g. 60 GHz), massive MTC (mMTC) targetingnon-backward compatible MTC techniques, and mission critical targetingultra reliable low latency communications (URLLC). For these generaltopics, different techniques are considered, such as coding, low-densityparity check (LDPC), and polar. NR cell may refer to a cell operatingaccording to the new air interface or fixed transport layer. A NR Node B(e.g., 5G Node B) may correspond to one or multiple transmissionreception points (TRPs).

NR cells can be configured as access cell (ACells) or data only cells(DCells). For example, the RAN (e.g., a central unit or distributedunit) can configure the cells. DCells may be cells used for carrieraggregation or dual connectivity, but not used for initial access, cellselection/reselection, or handover. In some cases DCells may nottransmit synchronization signals—in some case cases DCells may transmitSS. TRPs may transmit downlink signals to UEs indicating the cell type.Based on the cell type indication, the UE may communicate with the TRP.For example, the UE may determine TRPs to consider for cell selection,access, handover, and/or measurement based on the indicated cell type.

In some cases, the UE can receive measurement configuration from theRAN. The measurement configuration information may indicate ACells orDCells for the UE to measure. The UE may monitor/detect measurementreference signals from the cells based on measurement configurationinformation. In some cases, the UE may blindly detect MRS. In some casesthe UE may detect MRS based on MRS-IDs indicated from the RAN. The UEmay report the measurement results.

Various aspects of the disclosure are described more fully hereinafterwith reference to the accompanying drawings. This disclosure may,however, be embodied in many different forms and should not be construedas limited to any specific structure or function presented throughoutthis disclosure. Rather, these aspects are provided so that thisdisclosure will be thorough and complete, and will fully convey thescope of the disclosure to those skilled in the art. Based on theteachings herein one skilled in the art should appreciate that the scopeof the disclosure is intended to cover any aspect of the disclosuredisclosed herein, whether implemented independently of or combined withany other aspect of the disclosure. For example, an apparatus may beimplemented or a method may be practiced using any number of the aspectsset forth herein. In addition, the scope of the disclosure is intendedto cover such an apparatus or method which is practiced using otherstructure, functionality, or structure and functionality in addition toor other than the various aspects of the disclosure set forth herein. Itshould be understood that any aspect of the disclosure disclosed hereinmay be embodied by one or more elements of a claim.

The word “exemplary” is used herein to mean “serving as an example,instance, or illustration.” Any aspect described herein as “exemplary”is not necessarily to be construed as preferred or advantageous overother aspects.

Although particular aspects are described herein, many variations andpermutations of these aspects fall within the scope of the disclosure.Although some benefits and advantages of the preferred aspects arementioned, the scope of the disclosure is not intended to be limited toparticular benefits, uses, or objectives. Rather, aspects of thedisclosure are intended to be broadly applicable to different wirelesstechnologies, system configurations, networks, and transmissionprotocols, some of which are illustrated by way of example in thefigures and in the following description of the preferred aspects. Thedetailed description and drawings are merely illustrative of thedisclosure rather than limiting and the scope of the disclosure is beingdefined by the appended claims and equivalents thereof.

The techniques described herein may be used for various wirelesscommunication networks such as LTE, CDMA, TDMA, FDMA, OFDMA, SC-FDMA andother networks. The terms “network” and “system” are often usedinterchangeably. A CDMA network may implement a radio technology such asUniversal Terrestrial Radio Access (UTRA), cdma2000, etc. UTRA includesWideband CDMA (WCDMA) and other variants of CDMA. cdma2000 coversIS-2000, IS-95 and IS-856 standards. A TDMA network may implement aradio technology such as Global System for Mobile Communications (GSM).An OFDMA network may implement a radio technology such as NR (e.g. 5GRA), Evolved UTRA (E-UTRA), Ultra Mobile Broadband (UMB), IEEE 802.11(Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Flash-OFDMA, etc. UTRA andE-UTRA are part of Universal Mobile Telecommunication System (UMTS). NRis an emerging wireless communications technology under development inconjunction with the 5G Technology Forum (5GTF). 3GPP Long TermEvolution (LTE) and LTE-Advanced (LTE-A) are releases of UMTS that useE-UTRA. UTRA, E-UTRA, UMTS, LTE, LTE-A and GSM are described indocuments from an organization named “3rd Generation PartnershipProject” (3GPP). cdma2000 and UMB are described in documents from anorganization named “3rd Generation Partnership Project 2” (3GPP2). Thetechniques described herein may be used for the wireless networks andradio technologies mentioned above as well as other wireless networksand radio technologies. For clarity, while aspects may be describedherein using terminology commonly associated with 3G and/or 4G wirelesstechnologies, aspects of the present disclosure can be applied in othergeneration-based communication systems, such as 5G and later, includingNR technologies.

Example Wireless Communications System

FIG. 1 illustrates an example wireless network 100 in which aspects ofthe present disclosure may be performed. For example, the wirelessnetwork may be new radio or 5G network. UEs 120 may be configured toperform the operations 900 discussed in more detail below for processingCSI-RS, in accordance with aspects of the present disclosure. Node B 110may comprise a transmission reception point (TRP) configured to performthe operations 800 discussed in more detail below for transmittingCSI-RS, in accordance with aspects of the present disclosure. The NRnetwork may include the central unit. The new radio network 100 maycomprise a central unit 140. According to certain aspects, the UEs 120,Node B 110 (TRP), and central unit 140 may be configured to performoperations related to measurement configuration, measurement referencesignal transmission, monitoring, detection, measurement, and measurementreporting, which are described in greater detail below.

The system illustrated in FIG. 1 may be, for example, a long termevolution (LTE) network. The wireless network 100 may include a numberof Node Bs (e.g., evolved NodeBs (eNB), 5G Node B, etc.) 110 and othernetwork entities. A Node B may be a station that communicates with theUEs and may also be referred to as a base station, an access point, etc.A Node B and 5G Node B are other examples of stations that communicatewith the UEs.

Each Node B 110 may provide communication coverage for a particulargeographic area. In 3GPP, the term “cell” can refer to a coverage areaof a Node B and/or a Node B subsystem serving this coverage area,depending on the context in which the term is used.

A Node B may provide communication coverage for a macro cell, a picocell, a femto cell, and/or other types of cell. A macro cell may cover arelatively large geographic area (e.g., several kilometers in radius)and may allow unrestricted access by UEs with service subscription. Apico cell may cover a relatively small geographic area and may allowunrestricted access by UEs with service subscription. A femto cell maycover a relatively small geographic area (e.g., a home) and may allowrestricted access by UEs having association with the femto cell (e.g.,UEs in a Closed Subscriber Group (CSG), UEs for users in the home,etc.). A Node B for a macro cell may be referred to as a macro Node B. ANode B for a pico cell may be referred to as a pico Node B. A Node B fora femto cell may be referred to as a femto Node B or a home Node B. Inthe example shown in FIG. 1 , the Node Bs 110 a, 110 b and 110 c may bemacro Node Bs for the macro cells 102 a, 102 b and 102 c, respectively.The Node B 110 x may be a pico Node B for a pico cell 102 x. The Node Bs110 y and 110 z may be femto Node Bs for the femto cells 102 y and 102z, respectively. A Node B may support one or multiple (e.g., three)cells.

The wireless network 100 may also include relay stations. A relaystation is a station that receives a transmission of data and/or otherinformation from an upstream station (e.g., a Node B or a UE) and sendsa transmission of the data and/or other information to a downstreamstation (e.g., a UE or a Node B). A relay station may also be a UE thatrelays transmissions for other UEs. In the example shown in FIG. 1 , arelay station 110 r may communicate with the Node B 110 a and a UE 120 rin order to facilitate communication between the Node B 110 a and the UE120 r. A relay station may also be referred to as a relay Node B, arelay, etc.

The wireless network 100 may be a heterogeneous network that includesNode Bs of different types, e.g., macro Node Bs, pico Node Bs, femtoNode Bs, relays, transmission reception points (TRPs), etc. Thesedifferent types of Node Bs may have different transmit power levels,different coverage areas, and different impact on interference in thewireless network 100. For example, macro Node Bs may have a hightransmit power level (e.g., 20 Watts) whereas pico Node Bs, femto NodeBs and relays may have a lower transmit power level (e.g., 1 Watt).

The wireless network 100 may support synchronous or asynchronousoperation. For synchronous operation, the Node Bs may have similar frametiming, and transmissions from different Node Bs may be approximatelyaligned in time. For asynchronous operation, the Node Bs may havedifferent frame timing, and transmissions from different Node Bs may notbe aligned in time. The techniques described herein may be used for bothsynchronous and asynchronous operation.

A network controller 130 may couple to a set of Node Bs and providecoordination and control for these Node Bs. The network controller 130may communicate with the Node Bs 110 via a backhaul. The Node Bs 110 mayalso communicate with one another, e.g., directly or indirectly viawireless or wireline backhaul.

The UEs 120 (e.g., 120 x, 120 y, etc.) may be dispersed throughout thewireless network 100, and each UE may be stationary or mobile. A UE mayalso be referred to as a terminal, a mobile station, a subscriber unit,a station, etc. A UE may be a cellular phone, a personal digitalassistant (PDA), a wireless modem, a wireless communication device, ahandheld device, a laptop computer, a cordless phone, a wireless localloop (WLL) station, a tablet, a netbook, a smart book, etc. A UE may beable to communicate with macro Node Bs, pico Node Bs, femto Node Bs,relays, etc. In FIG. 1 , a solid line with double arrows indicatesdesired transmissions between a UE and a serving Node B, which is a NodeB designated to serve the UE on the downlink and/or uplink. A dashedline with double arrows indicates interfering transmissions between a UEand a Node B.

LTE utilizes orthogonal frequency division multiplexing (OFDM) on thedownlink and single-carrier frequency division multiplexing (SC-FDM) onthe uplink. OFDM and SC-FDM partition the system bandwidth into multiple(K) orthogonal subcarriers, which are also commonly referred to astones, bins, etc. Each subcarrier may be modulated with data. Ingeneral, modulation symbols are sent in the frequency domain with OFDMand in the time domain with SC-FDM. The spacing between adjacentsubcarriers may be fixed, and the total number of subcarriers (K) may bedependent on the system bandwidth. For example, the spacing of thesubcarriers may be 15 kHz and the minimum resource allocation (called a‘resource block’) may be 12 subcarriers (or 180 kHz). Consequently, thenominal FFT size may be equal to 128, 256, 512, 1024 or 2048 for systembandwidth of 1.25, 2.5, 5, 10 or 20 megahertz (MHz), respectively. Thesystem bandwidth may also be partitioned into subbands. For example, asubband may cover 1.08 MHz (i.e., 6 resource blocks), and there may be1, 2, 4, 8 or 16 subbands for system bandwidth of 1.25, 2.5, 5, 10 or 20MHz, respectively.

While aspects of the examples described herein may be associated withLTE technologies, aspects of the present disclosure may be applicablewith other wireless communications systems, such as NR. NR may utilizeOFDM with a CP on the uplink and downlink and include support forhalf-duplex operation using TDD. A single component carrier bandwidth of100 MHZ may be supported. Each radio frame may be 10 ms long and consistof 50 slots. Consequently, each slot may have a length of 0.2 ms. Inalternative embodiments, each slot may have a length of 0.5 ms. In NR,“slots” may also refer to “mini-slots,” which may be one to two symbolperiods long. Each slot may indicate a link direction (i.e., DL or UL)for data transmission and the link direction for each slot may bedynamically switched. Each slot may include DL and/or UL data as well asDL and/or UL control data. Beamforming may be supported and beamdirection(s) may be dynamically configured. MIMO transmissions withprecoding may also be supported. Alternatively, NR may support adifferent air interface, other than an OFDM-based interface. NR networksmay include entities such as central units, distributed units, datanodes, access nodes, and access control nodes.

FIG. 2 shows an exemplary downlink (DL) frame structure used in atelecommunication systems (e.g., LTE). The transmission timeline for thedownlink may be partitioned into units of radio frames. Each radio framemay have a predetermined duration (e.g., 10 milliseconds (ms)) and maybe partitioned into 20 slots with indices of 0 through 19. Each slot mayinclude L symbol periods, e.g., 7 symbol periods for a normal cyclicprefix (as shown in FIG. 2 ). The available time frequency resources maybe partitioned into resource blocks. Each resource block may cover Nsubcarriers (e.g., 12 subcarriers) in one slot.

The Node B may send a downlink control channel (e.g., a physicaldownlink control channel (PDCCH)) in the first M symbol periods of eachslot (M=3 in FIG. 2 ). The downlink control channel may carryinformation on uplink and downlink resource allocation for UEs and powercontrol information for uplink channels. The Node B may send a physicaldownlink shared channel (PDSCH) in the remaining symbol periods of eachslot. The PDSCH may carry data for UEs scheduled for data transmissionon the downlink. There may also be an uplink burst at the end of theslot.

The Node B may send the PDCCH to groups of UEs or in a unicast manner tospecific UEs in certain portions of the system bandwidth. The Node B maysend the PDSCH in a unicast manner to specific UEs in specific portionsof the system bandwidth.

A UE may be within the coverage of multiple Node Bs. One of these NodeBs may be selected to serve the UE. The serving Node B may be selectedbased on various criteria such as received power, path loss,signal-to-noise ratio (SNR), etc.

FIG. 3 is a diagram 300 illustrating an example of an uplink (UL) framestructure in a telecommunications system (e.g., LTE). The availableresource blocks for the UL may be partitioned into a data section and acontrol section. The control section may be formed at the two edges ofthe system bandwidth and may have a configurable size. The resourceblocks in the control section may be assigned to UEs for transmission ofcontrol information. The data section may include all resource blocksnot included in the control section. The UL frame structure results inthe data section including contiguous subcarriers, which may allow asingle UE to be assigned all of the contiguous subcarriers in the datasection.

A UE may be assigned resource blocks 310 a, 310 b to transmit controlinformation to a Node B. The UE may also be assigned resource blocks 320a, 320 b to transmit data to the Node B. The UE may transmit controlinformation in a physical UL control channel (PUCCH) on the assignedresource blocks. The UE may transmit only data or both data and controlinformation in a physical UL shared channel (PUSCH) on the assignedresource blocks in the data section. A UL transmission may hop acrossfrequency.

FIG. 4 illustrates example components of the base station/Node B 110 andUE 120 illustrated in FIG. 1 , which may be used to implement aspects ofthe present disclosure. One or more components of the AP 110 and UE 120may be used to practice aspects of the present disclosure. For example,antennas 452, Tx/Rx 222, processors 466, 458, 464, and/orcontroller/processor 480 of the UE 120 and/or antennas 434, processors460, 420, 438, and/or controller/processor 440 of the BS 110 may be usedto perform the operations described herein and illustrated withreference to FIGS. 7-8 .

FIG. 4 shows a block diagram of a design of a base station/Node B 110and a UE 120, which may be one of the base stations/Node Bs and one ofthe UEs in FIG. 1 . For a restricted association scenario, the basestation 110 may be the macro Node B 110 c in FIG. 1 , and the UE 120 maybe the UE 120 y. The base station 110 may also be a base station of someother type. The base station 110 may be equipped with antennas 434 athrough 434 t, and the UE 120 may be equipped with antennas 452 athrough 452 r.

At the base station 110, a transmit processor 420 may receive data froma data source 412 and control information from a controller/processor440. The control information may be for the PBCH, PCFICH, PHICH, PDCCH,etc. The data may be for the PDSCH, etc. The processor 420 may process(e.g., encode and symbol map) the data and control information to obtaindata symbols and control symbols, respectively. The processor 420 mayalso generate reference symbols, e.g., for the PSS, SSS, andcell-specific reference signal. A transmit (TX) multiple-inputmultiple-output (MIMO) processor 430 may perform spatial processing(e.g., precoding) on the data symbols, the control symbols, and/or thereference symbols, if applicable, and may provide output symbol streamsto the modulators (MODs) 432 a through 432 t. Each modulator 432 mayprocess a respective output symbol stream (e.g., for OFDM, etc.) toobtain an output sample stream. Each modulator 432 may further process(e.g., convert to analog, amplify, filter, and upconvert) the outputsample stream to obtain a downlink signal. Downlink signals frommodulators 432 a through 432 t may be transmitted via the antennas 434 athrough 434 t, respectively.

At the UE 120, the antennas 452 a through 452 r may receive the downlinksignals from the base station 110 and may provide received signals tothe demodulators (DEMODs) 454 a through 454 r, respectively. Eachdemodulator 454 may condition (e.g., filter, amplify, downconvert, anddigitize) a respective received signal to obtain input samples. Eachdemodulator 454 may further process the input samples (e.g., for OFDM,etc.) to obtain received symbols. A MIMO detector 456 may obtainreceived symbols from all the demodulators 454 a through 454 r, performMIMO detection on the received symbols if applicable, and providedetected symbols. A receive processor 458 may process (e.g., demodulate,deinterleave, and decode) the detected symbols, provide decoded data forthe UE 120 to a data sink 460, and provide decoded control informationto a controller/processor 480.

On the uplink, at the UE 120, a transmit processor 464 may receive andprocess data (e.g., for the PUSCH) from a data source 462 and controlinformation (e.g., for the PUCCH) from the controller/processor 480. Thetransmit processor 464 may also generate reference symbols for areference signal. The symbols from the transmit processor 464 may beprecoded by a TX MIMO processor 466 if applicable, further processed bythe demodulators 454 a through 454 r (e.g., for SC-FDM, etc.), andtransmitted to the base station 110. At the base station 110, the uplinksignals from the UE 120 may be received by the antennas 434, processedby the modulators 432, detected by a MIMO detector 436 if applicable,and further processed by a receive processor 438 to obtain decoded dataand control information sent by the UE 120. The receive processor 438may provide the decoded data to a data sink 439 and the decoded controlinformation to the controller/processor 440.

The controllers/processors 440 and 480 may direct the operation at thebase station 110 and the UE 120, respectively. The processor 440 and/orother processors and modules at the base station 110 may perform ordirect, e.g., the execution of various processes for the techniquesdescribed herein. The processor 480 and/or other processors and modulesat the UE 120 may also perform or direct, e.g., the execution of thefunctional blocks illustrated in FIGS. 12-14 , and/or other processesfor the techniques described herein. The memories 442 and 482 may storedata and program codes for the base station 110 and the UE 120,respectively. A scheduler 444 may schedule UEs for data transmission onthe downlink and/or uplink.

FIG. 5 is a diagram 500 illustrating an example of a radio protocolarchitecture for the user and control planes in LTE. The radio protocolarchitecture for the UE and the Node B is shown with three layers: Layer1, Layer 2, and Layer 3. Layer 1 (L1 layer) is the lowest layer andimplements various physical layer signal processing functions. The L1layer will be referred to herein as the physical layer 506. Layer 2 (L2layer) 508 is above the physical layer 506 and is responsible for thelink between the UE and Node B over the physical layer 506.

In the user plane, the L2 layer 508 includes a media access control(MAC) sublayer 510, a radio link control (RLC) sublayer 512, and apacket data convergence protocol (PDCP) 514 sublayer, which areterminated at the Node B on the network side. Although not shown, the UEmay have several upper layers above the L2 layer 508 including a networklayer (e.g., IP layer) that is terminated at the PDN gateway 118 on thenetwork side, and an application layer that is terminated at the otherend of the connection (e.g., far end UE, server, etc.).

The PDCP sublayer 514 provides multiplexing between different radiobearers and logical channels. The PDCP sublayer 514 also provides headercompression for upper layer data packets to reduce radio transmissionoverhead, security by ciphering the data packets, and handover supportfor UEs between Node Bs. The RLC sublayer 512 provides segmentation andreassembly of upper layer data packets, retransmission of lost datapackets, and reordering of data packets to compensate for out-of-orderreception due to hybrid automatic repeat request (HARQ). The MACsublayer 510 provides multiplexing between logical and transportchannels. The MAC sublayer 510 is also responsible for allocating thevarious radio resources (e.g., resource blocks) in one cell among theUEs. The MAC sublayer 510 is also responsible for HARQ operations.

In the control plane, the radio protocol architecture for the UE andNode B is substantially the same for the physical layer 506 and the L2layer 508 with the exception that there is no header compressionfunction for the control plane. The control plane also includes a radioresource control (RRC) sublayer 516 in Layer 3 (L3 layer). The RRCsublayer 516 is responsible for obtaining radio resources (i.e., radiobearers) and for configuring the lower layers using RRC signalingbetween the Node B and the UE.

New radio (NR) may refer to radios configured to operate according awireless standard, such as 5G (e.g. wireless network 100). NR mayinclude Enhanced mobile broadband (eMBB) targeting wide bandwidth (e.g.80 MHz and beyond), millimeter wave (mmW) targeting high carrierfrequency (e.g. 27 GHz and higher), massive MTC (mMTC) targetingnon-backward compatible MTC techniques, and mission critical targetingultra reliable low latency communications (URLLC).

NR cell may refer to a cell operating according in the NR network. A NRNode B (e.g., Node B 110) may correspond to one or multiple transmissionand reception points (TRPs). As used herein, a cell may refer to acombination of downlink (and potentially also uplink) resources. Thelinking between the carrier frequency of the downlink resources and thecarrier frequency of the uplink resources is indicated in the systeminformation (SI) transmitted on the downlink resources. For example,system information can be transmitted in a physical broadcast channel(PBCH) carrying a master information block (MIB).

NR RAN architecture may include a central unit (CU) (e.g., central unit140). The CU may be an Access node controller (ANC). The CU terminatesbackhaul interface to a RAN core network (RAN-CN) and terminatesbackhaul interface to one or more neighbor RAN nodes. The RAN mayinclude a distributed unit that may be one or more TRPs that may beconnected to one or more ANCs (not shown). TRPs may advertise SystemInformation (e.g., Global TRP ID), may include PDCP/RLC/MAC functions,may comprise one or more antenna ports, may be configured toindividually (dynamic selection) or jointly (joint transmission)transmit to UEs, and may serve traffic to the UE.

FIG. 6 shows another exemplary transmission timeline 600 that may beused in a TDD system in which one or more aspects of the presentdisclosure may be practiced. The timeline 600 is divided into aplurality of slots 602 or 610. A slot is a scheduling unit that has DLcontrol, data, and UL control, as shown. A mini-slot is the smallerscheduling unit that 5G will support. A mini-slot can be as small as 1or 2 OFDM symbols and can have DL control, data, and UL control.According to aspects of the present disclosure, slots in a TDDcommunications system may be UL-centric or DL-centric. An UL-centricslot is a slot with a majority of OFDM symbols of the slot used for ULtransmission(s). An UL-centric slot typically has a few (e.g. 2) DLsymbols at the beginning, then a guard duration, then UL symbols. ADL-centric slot is a slot with a majority of OFDM symbols used for DLtransmission. A DL-centric slot typically has most (e.g. 12) of thefirst symbols used for DL transmissions, then a guard interval, then afew (e.g., 1-2) UL symbols. The timeline 600 includes a pluralityDL-centric slots 602 that have most symbols 604 dedicated to DLtransmissions (e.g., from a BS to a UE) and a common UL burst 606 at theend with very limited resources dedicated to UL transmissions (e.g.,from a UE to a BS). The timeline also includes a plurality of UL-centricslots 610 that each has a DL symbol 612 at the beginning of the slot,but the remaining symbols 614 of the slot are dedicated to ULtransmissions. As seen in the UL slot 610 b, the UL symbols 614 may beallocated to various users (e.g., UEs) for a variety of UL transmissions(e.g., OFDM PUSCH, SC-FDM PUSCH, SC-FDM PUCCH, OFDM PUCCH). Similarly,while not shown, the DL symbols 604 of a DL slot 602 may be allocatedfor a variety of DL transmissions (e.g., PDCCH, PDSCH) to one or moreUEs.

According to aspects of the present disclosure, DL-centric slots andUL-centric slots may occur according to a ratio configurable by thenetwork (e.g., a network controller). The ratio of DL-centric slots andUL-centric slots may be of the order of 4:1, 10:1, etc., i.e., there maybe significantly more DL-centric slots than UL-centric slots in manywireless communications systems.

Example of Transmitting Channel State Information Reference Signals inNew Radio

MIMO may be an important technology enabler for satisfying NR coverageand capacity requirements. The advantages of using MIMO come at theprice of obtaining channel state information (CSI) at thetransmission/reception point (TRP). The CSI has to be obtained at theTRP via UE feedback based on DL channel estimation by the UE(s), aidedby CSI-RS transmitted by the TRP and processed by the UE(s).

FIG. 7 illustrates an exemplary resource block structure 700 showing amapping of CSI-RSs to resource elements in an LTE communications system,according to aspects of the present disclosure. In an LTE communicationssystem, up to 40 resource elements (REs) may be reserved for CSI-RStransmission in FDD. The 40 REs that may be reserved for CSI-RStransmission are shown at 702, 704, 706, 708, 710, 712, 714, 716, 718,and 720 labeled as sets A through J of REs, with 4 REs per set. Sets Athrough J are capable of supporting 10 CSI-RSs, as shown in FIG. 7 . Ifa cell transmits CSI-RS using 2 CSI-RS ports, then the 2 CSI-RS portsmay be multiplexed by size-2 orthogonal cover codes (OCC) in the timedomain. If a cell transmits CSI-RS using 4 CSI-RS ports, then the 4CSI-RS ports may be multiplexed by applying size-4 OCC in both the timeand the frequency domain. Orthogonal cover codes (OCC) provideadditional orthogonality between the CSI-RS ports.

According to aspects of the present disclosure, an NR TRP may determinea configuration of CSI-RSs in resource elements, transmit an indicationof the determined configuration, and transmit the CSI-RSs according tothe configuration. A UE may obtain the indication of the determinedconfiguration, process CSI-RSs based on the indicated configuration todetermine channel state information, and report the channel stateinformation to the TRP. Operation of a massive MIMO wirelesscommunication system heavily relies on a variety of procedures andmechanisms to provide channel state information (CSI) at the transmitterfor achieving high beamforming and spatial multiplexing gains. The TRPreceiving the CSI may then use the CSI for downlink scheduling by a BS.

According to aspects of the present disclosure, the provided techniquesfor mapping CSI-RSs to REs may support at least 32 ports while using asmaller footprint, in terms of transmission resources, than othertechniques.

According to aspects of the present disclosure, the provided techniquesfor mapping CSI-RSs to REs may support both beamformed and non-precodedCSI-RS. Power boosting of CSI-RS may improve coverage for UEs in poorcoverage conditions.

According to aspects of the present disclosure, the provided techniquesfor mapping CSI-RSs to REs may support both 7-symbol-period and14-symbol-period slots, as well as mini-slots having a length in symbolperiods from one to a slot-length minus one (e.g., 7−1=6 symbol periodmini-slot or 14−1=13 symbol period mini-slot).

According to aspects of the present disclosure, the provided techniquesfor mapping CSI-RSs to REs may support CSI-RS resource pooling.

According to aspects of the present disclosure, the provided techniquesfor mapping CSI-RSs to REs may support transmissions usingself-contained slots. A self-contained slot is a slot in which a TRPtransmits a control channel scheduling an UL transmission (e.g., aPUSCH) or a DL transmission (e.g., a PDSCH) in the same slot. The datatransmission occurs in the same slot, and if the data transmission was aDL transmission, then a UE that received the DL transmission transmitsan acknowledgment (ACK) in the same slot. This is referred to as aself-contained slot because the TRP starts a transmission (e.g., thePDCCH) in a slot and receives an indication that the transmission wassuccessful (e.g., the PUSCH or the ACK) in the same slot.

FIG. 8 illustrates example operations 800 for wireless communications bya TRP, according to aspects of the present disclosure. The operations800 may be performed, for example, by BS 110 shown in FIG. 1 .

Operations 800 begin, at block 802 by determining a configuration ofchannel state information reference signals (CSI-RSs), wherein theconfiguration indicates a set of resource elements (REs) to be used forCSI-RSs and a first mapping of CSI-RS ports to the set of REs. Forexample, BS 110 determines a configuration of CSI-RSs (e.g., theconfiguration illustrated in FIG. 10 , described below), wherein theconfiguration indicates a set of REs to be used for CSI-RSs and a firstmapping (e.g., the mapping shown in FIG. 10 ) of CSI-RS ports to the setof REs.

At block 804, operations 800 continue with sending an indication of theconfiguration of the CSI-RSs. Continuing the example from above, BS 110sends (e.g., transmits) an indication (e.g., via radio resource control(RRC), layer 2 (L2), and/or layer 1 (L1) signaling) of the configurationof the CSI-RSs.

Operations 800 continue, at block 806, with transmitting the CSI-RSsaccording to the determined configuration. Continuing the example fromabove, BS 110 transmits the CSI-RSs according to the configurationdetermined in block 802 (e.g., the configuration illustrated in FIG. 10, described below).

FIG. 9 is a flowchart illustrating example operations 900 for wirelesscommunications by a wireless node, according to aspects of the presentdisclosure. The operations 900 may be performed by, for example, a UE(e.g., UE 120). Operations 900 may be considered UE-side operationsperformed to process CSI-RS transmitted in accordance with operations800 described above.

Operations 900 begin, at block 902, by the wireless node obtaining anindication of a configuration of channel state information referencesignals (CSI-RSs) from a transmission and reception point (TRP), whereinthe configuration indicates a set of resource elements (REs) to be usedfor CSI-RSs and a first mapping of CSI-RS ports to the set of REs. Forexample, UE 120, shown in FIG. 1 , obtains (e.g., receives via RRC, L2,and/or L1 signaling) an indication of a configuration (e.g., theconfiguration illustrated in FIG. 10 ) from a TRP (e.g., BS 110 a, shownin FIG. 1 ), wherein the configuration indicates a set of REs to be usedfor CSI-RSs and a first mapping of CSI-RS ports to the set of REs.

Operations 900 continue, at block 904, by the wireless node processingCSI-RSs based on the indicated configuration to determine channel stateinformation. Continuing the example from above, the UE 120 processes(e.g., measures) CSI-RSs based on the indicated configuration (fromblock 902) to determine channel state information.

At block 906, the UE reports the channel state information to the TRP.Continuing the example from above, the UE 120 reports (e.g., bytransmitting a CSI report) the channel state information to the TRP(e.g., BS 110 a, shown in FIG. 1 ).

Control signaling can be used to indicate one symbol (self-containedCSI-RS symbol) or more than 1 symbol with OCC and possibly somecombinations of one symbol and two symbols in a slot: for example, for a7-symbol slot, 3 pairs of CSI-RS symbols plus 1 CSI-RS symbol may beused.

In some cases, configurable orthogonal cover codes (OCC) may be appliedin time and/or frequency. The OCC configuration may be indicated viahigher-layer signaling (e.g., RRC), L2 signaling (e.g., a MAC CE), L1signaling (e.g., a DCI) and/or any combination of RRC, L2, or L1signaling.

In some cases, scalable numerology symbols for 1-symbol CSI-RS may beused to create two virtual symbols, for example, by applying OCC in time(time domain OCC (TD-OCC)). For example, instead of transmitting oneOFDM symbol with a first numerology, two OFDM symbols with a secondnumerology with double subcarrier spacing (SCS) and the same cyclicprefix (CP) overhead are transmitted. These two symbols can carry theCSI-RS using TD-OCC.

The location (in time domain) of CSI-RS may be determined relative tothe end of the DL portion, when a self-contained slot is used. Forexample, if one OFDM symbol with CSI-RS is used, this symbol isimplicitly understood that it is the latest (e.g., last) DL symbol inthe DL burst. Similarly, if two or more symbols carrying CSI-RS areused, then the last two or more latest symbols of the DL burst are beingused for CSI-RS. In this example, data shall not be multiplexed withCSI-RS on the same symbols.

As illustrated in FIG. 10 , with “1-symbol CSI-RS,” a CSI-RStransmission may be self-contained in one OFDM symbol. According to someaspects of the present disclosure, a 1-symbol CSI-RS may be aself-contained CSI-RS transmitted using interleaved frequency divisionmultiplexing (IFDM) and/or code division multiplexing (CDM). Asillustrated, the CSI-RS may be transmitted on uniformly distributed REs.The CSI-RS resources correspond to RE groups. Different CSI-RS ports maybe separated by using different combs, labeled combs A, B, C, and D andshown at 1002, and/or using different cyclic-shifts of a common rootconstant amplitude zero autocorrelation (CAZAC) sequence (e.g., aZadoff-Chu sequence). As illustrated, there are 12 ports. Comb Acorresponds to frequencies 0, 4, and 8. Likewise, comb B corresponds tofrequencies 1, 5, and 9; comb C corresponds to frequencies 2, 6, and 10;and comb D corresponds to frequencies 3, 7, and 11. A series ofdiscrete, equally spaced elements in a spectrum may be referred to as afrequency comb.

FIGS. 11A and 11B illustrate other examples of 1-symbol CSI-RStransmission with frequency division multiplexing (FDM) and/or frequencydivision orthogonal cover codes (FD-OCC). As illustrated, the CSI-RS maybe transmitted on a set of uniformly distributed RE groups. Each groupmay comprise two or more localized or distributed REs. Different CSI-RSports may be separated by different sets of RE groups and further byapplying orthogonal cover codes (OCC) to the REs in each group. In FIG.11A, it can be seen that there are 6 CSI-RS configurations, A-F, witheach set (e.g. set A, set B, . . . or set F) of CSI-RS ports beingmapped to 2 REs that are located in a same time domain (e.g., OFDMsymbol 13) and adjacent each other (e.g., on consecutive subcarriers) inthe frequency domain, as shown at 1102. This may result in a strongercorrelation of each CSI when combining the CSI-RS resources. Resourceconfiguration set A comprises ports 0 and 1 with size-2 frequency domainorthogonal cover codes (FD-OCC2). Resource configuration set B comprisesports 2 and 3 with FD-OCC2. Resource configuration set C comprises ports4 and 5 with FD-OCC2. Resource configuration set D comprises ports 6 and7 with FD-OCC2. Resource configuration set E comprises ports 8 and 9with FD-OCC2. Resource configuration set F comprises ports 10 and 11with FD-OCC2. In FIG. 11B, it can be seen that there are 12 CSI-RSconfigurations at 1152, each CSI-RS resource or port being mapped to 1RE.

FIGS. 12A and 12B illustrate 2-symbol CSI-RS, with each CSI-RStransmission using a pair of OFDM symbols with TD-OCC, in accordancewith aspects of the present disclosure. A UE can be configured tofurther apply orthogonal cover codes (OCC) to two OFDM symbols. TD-OCCmay be configurable for the 2-symbol CSI-RS solution. The configurationcan be either signaled using higher-layer signaling (e.g., RRC), L2signaling (e.g., MAC CE), L1 signaling (e.g., DCI), and/or anycombination of higher-layer signaling, L2 signaling, or L1 signaling.FIG. 12A illustrates an example of mapping CSI-RS with IFDM and/or CDMand TD-OCC at 1202. FIG. 12B illustrates an example of mapping CSI-RSwith FDM and FD-OCC and/or TD-OCC at 1252.

FIGS. 13A and 13B illustrate examples of multiple 1-symbol CSI-RStransmissions in a slot, in accordance with aspects of the presentdisclosure. A UE may be configured with one or more OFDM symbols for1-symbol CSI-RS transmission. For example, in case of 24-port CSI-RS, aUE may be configured with CSI-RS transmission on 2 OFDM symbols; onesymbol may convey CSI-RS ports 0-11, as shown at 1302, and the othersymbol may convey CSI-RS ports 12-23, as shown at 1304. In anotherexample, the ports may be divided into twelve sets of CSI-RS resources,while still having a first symbol convey CSI-RS ports 0-11, as shown at1352, and another symbol conveying CSI-RS ports 12-23, as shown at 1354.

FIG. 14 illustrates an example of a combination (e.g., a mix) of1-symbol and 2-symbol CSI-RSs in a slot. In the illustrated example, aUE may be configured with one or more 1-symbol and/or 2-symbol CSI-RSs.For example, in case of a 7-symbol slot, a UE can be configured w/three2-symbol CSI-RSs with TD-OCC2, shosn at 1402, 1404, and 1406, and a1-symbol CSI-RS 1410. The configuration may be signaled usinghigher-layer signaling (e.g., RRC), L2 signaling (e.g., MAC CE), L1signaling (e.g., DCI), and/or any combination of higher-layer signaling,L2 signaling, and L1 signaling. The configuration may indicate whichsymbols are used for 1-symbol CSI-RS and which symbols are used for2-symbol CSI-RS. A 1-symbol CSI-RS can be virtually split into 2-symbolCSI-RS with TD-OCC2.

When only 1-symbol is available, and TD-OCC is configured, then scalednumerology (double subcarrier spacing with the same CP overhead) may beused to create 2-symbols with double the subcarrier spacing (SCS) andapplying TD-OCC.

According to aspects of the present disclosure, similar techniques maybe applied for CSI-RS in a mini-slot. A mini-slot is generally theminimum scheduling unit that can be as small as 1 OFDM symbol and up toslot length-1 (e.g., 7−1=6) OFDM symbols. For all cases that the numberof available CSI-RS symbols is odd, 1-symbol and 2-symbol CSI-RS designsmay be mixed.

FIG. 15A illustrates an example of CSI-RS location in a self-containedslot. For low-latency applications, symbols carrying CSI-RS may beallocated relative to the “end” of the DL part of the slot, as shown at1502. The same technique may be applied to aggregation of slots ormini-slots. CSI-RS and data may not be frequency division multiplexed inthese symbols. If frequency division multiplexing of data and CSI-RS wassupported, then data would appear in the last symbols, which would makethe timeline processing and the fast-turnaround of the ACK difficult forthe UE.

According to aspects of the present disclosure and as illustrated inFIG. 15B, TD-OCC may be used to ensure that no resources are leftunused. For example, if 6 ports need to be supported, if no TD-OCC isused, then 4 ports will appear in one symbol, and 2 ports in the othersymbol. Then, some resource elements may not be allowed to carry data,and therefore these resources are lost. As shown at 1502 and 1504, eightports may be supported in a set of eight REs, both without using TD-OCC,as at 1502, and using TD-OCC, as at 1504. If only six ports are to besupported by the same set of eight REs, then two REs remain unused ifTD-OCC is not used, because six REs are used for the six CSI-RS and twoREs 1512 and 1514 are not needed for CSI-RS, but cannot be used for datatransmission (because data and CSI-RS frequency division multiplexing isnot supported). However, using TD-OCC with CSI-RS uses all of the REs,as shown at 1520, while allowing a stronger correlation of each CSI whencombining the CSI-RS.

The methods disclosed herein comprise one or more steps or actions forachieving the described method. The method steps and/or actions may beinterchanged with one another without departing from the scope of theclaims. In other words, unless a specific order of steps or actions isspecified, the order and/or use of specific steps and/or actions may bemodified without departing from the scope of the claims.

As used herein, a phrase referring to “at least one of” a list of itemsrefers to any combination of those items, including single members. Asan example, “at least one of: a, b, or c” is intended to cover a, b, c,a-b, a-c, b-c, and a-b-c, as well as any combination with multiples ofthe same element (e.g., a-a, a-a-a, a-a-b, a-a-c, a-b-b, a-c-c, b-b,b-b-b, b-b-c, c-c, and c-c-c or any other ordering of a, b, and c).

As used herein, the term “determining” encompasses a wide variety ofactions. For example, “determining” may include calculating, computing,processing, deriving, investigating, looking up (e.g., looking up in atable, a database or another data structure), ascertaining and the like.Also, “determining” may include receiving (e.g., receiving information),accessing (e.g., accessing data in a memory) and the like. Also,“determining” may include resolving, selecting, choosing, establishingand the like.

The previous description is provided to enable any person skilled in theart to practice the various aspects described herein. Variousmodifications to these aspects will be readily apparent to those skilledin the art, and the generic principles defined herein may be applied toother aspects. Thus, the claims are not intended to be limited to theaspects shown herein, but is to be accorded the full scope consistentwith the language claims, wherein reference to an element in thesingular is not intended to mean “one and only one” unless specificallyso stated, but rather “one or more.” Unless specifically statedotherwise, the term “some” refers to one or more. All structural andfunctional equivalents to the elements of the various aspects describedthroughout this disclosure that are known or later come to be known tothose of ordinary skill in the art are expressly incorporated herein byreference and are intended to be encompassed by the claims. Moreover,nothing disclosed herein is intended to be dedicated to the publicregardless of whether such disclosure is explicitly recited in theclaims. No claim element is to be construed under the provisions of 35U.S.C. § 112, sixth paragraph, unless the element is expressly recitedusing the phrase “means for” or, in the case of a method claim, theelement is recited using the phrase “step for.”

The various operations of methods described above may be performed byany suitable means capable of performing the corresponding functions.The means may include various hardware and/or software component(s)and/or module(s), including, but not limited to a circuit, anapplication specific integrated circuit (ASIC), or processor. Generally,where there are operations illustrated in figures, those operations mayhave corresponding counterpart means-plus-function components withsimilar numbering.

The various illustrative logical blocks, modules and circuits describedin connection with the present disclosure may be implemented orperformed with a general purpose processor, a digital signal processor(DSP), an application specific integrated circuit (ASIC), a fieldprogrammable gate array (FPGA) or other programmable logic device (PLD),discrete gate or transistor logic, discrete hardware components, or anycombination thereof designed to perform the functions described herein.A general-purpose processor may be a microprocessor, but in thealternative, the processor may be any commercially available processor,controller, microcontroller, or state machine. A processor may also beimplemented as a combination of computing devices, e.g., a combinationof a DSP and a microprocessor, a plurality of microprocessors, one ormore microprocessors in conjunction with a DSP core, or any other suchconfiguration.

If implemented in hardware, an example hardware configuration maycomprise a processing system in a wireless node. The processing systemmay be implemented with a bus architecture. The bus may include anynumber of interconnecting buses and bridges depending on the specificapplication of the processing system and the overall design constraints.The bus may link together various circuits including a processor,machine-readable media, and a bus interface. The bus interface may beused to connect a network adapter, among other things, to the processingsystem via the bus. The network adapter may be used to implement thesignal processing functions of the PHY layer. In the case of a userterminal 120 (see FIG. 1 ), a user interface (e.g., keypad, display,mouse, joystick, etc.) may also be connected to the bus. The bus mayalso link various other circuits such as timing sources, peripherals,voltage regulators, power management circuits, and the like, which arewell known in the art, and therefore, will not be described any further.The processor may be implemented with one or more general-purpose and/orspecial-purpose processors. Examples include microprocessors,microcontrollers, DSP processors, and other circuitry that can executesoftware. Those skilled in the art will recognize how best to implementthe described functionality for the processing system depending on theparticular application and the overall design constraints imposed on theoverall system.

If implemented in software, the functions may be stored or transmittedover as one or more instructions or code on a computer-readable medium.Software shall be construed broadly to mean instructions, data, or anycombination thereof, whether referred to as software, firmware,middleware, microcode, hardware description language, or otherwise.Computer-readable media include both computer storage media andcommunication media including any medium that facilitates transfer of acomputer program from one place to another. The processor may beresponsible for managing the bus and general processing, including theexecution of software modules stored on the machine-readable storagemedia. A computer-readable storage medium may be coupled to a processorsuch that the processor can read information from, and write informationto, the storage medium. In the alternative, the storage medium may beintegral to the processor. By way of example, the machine-readable mediamay include a transmission line, a carrier wave modulated by data,and/or a computer readable storage medium with instructions storedthereon separate from the wireless node, all of which may be accessed bythe processor through the bus interface. Alternatively, or in addition,the machine-readable media, or any portion thereof, may be integratedinto the processor, such as the case may be with cache and/or generalregister files. Examples of machine-readable storage media may include,by way of example, RAM (Random Access Memory), flash memory, ROM (ReadOnly Memory), PROM (Programmable Read-Only Memory), EPROM (ErasableProgrammable Read-Only Memory), EEPROM (Electrically ErasableProgrammable Read-Only Memory), registers, magnetic disks, opticaldisks, hard drives, or any other suitable storage medium, or anycombination thereof. The machine-readable media may be embodied in acomputer-program product.

A software module may comprise a single instruction, or manyinstructions, and may be distributed over several different codesegments, among different programs, and across multiple storage media.The computer-readable media may comprise a number of software modules.The software modules include instructions that, when executed by anapparatus such as a processor, cause the processing system to performvarious functions. The software modules may include a transmissionmodule and a receiving module. Each software module may reside in asingle storage device or be distributed across multiple storage devices.By way of example, a software module may be loaded into RAM from a harddrive when a triggering event occurs. During execution of the softwaremodule, the processor may load some of the instructions into cache toincrease access speed. One or more cache lines may then be loaded into ageneral register file for execution by the processor. When referring tothe functionality of a software module below, it will be understood thatsuch functionality is implemented by the processor when executinginstructions from that software module.

Also, any connection is properly termed a computer-readable medium. Forexample, if the software is transmitted from a website, server, or otherremote source using a coaxial cable, fiber optic cable, twisted pair,digital subscriber line (DSL), or wireless technologies such as infrared(IR), radio, and microwave, then the coaxial cable, fiber optic cable,twisted pair, DSL, or wireless technologies such as infrared, radio, andmicrowave are included in the definition of medium. Disk and disc, asused herein, include compact disc (CD), laser disc, optical disc,digital versatile disc (DVD), floppy disk, and Blu-ray® disc where disksusually reproduce data magnetically, while discs reproduce dataoptically with lasers. Thus, in some aspects computer-readable media maycomprise non-transitory computer-readable media (e.g., tangible media).In addition, for other aspects computer-readable media may comprisetransitory computer-readable media (e.g., a signal). Combinations of theabove should also be included within the scope of computer-readablemedia.

Thus, certain aspects may comprise a computer program product forperforming the operations presented herein. For example, such a computerprogram product may comprise a computer-readable medium havinginstructions stored (and/or encoded) thereon, the instructions beingexecutable by one or more processors to perform the operations describedherein. For example, instructions for determining a maximum availabletransmit power of the UE, instructions for semi-statically configuring afirst minimum guaranteed power available for uplink transmission to afirst base station and a second minimum guaranteed power available foruplink transmission to a second base station, and instructions fordynamically determining a first maximum transmit power available foruplink transmission to the first base station and a second maximumtransmit power available for uplink transmission to the second basestation based, at least in part, on the maximum available transmit powerof the UE, the first minimum guaranteed power, and the second minimumguaranteed power.

Further, it should be appreciated that modules and/or other appropriatemeans for performing the methods and techniques described herein can bedownloaded and/or otherwise obtained by a user terminal and/or basestation as applicable. For example, such a device can be coupled to aserver to facilitate the transfer of means for performing the methodsdescribed herein. Alternatively, various methods described herein can beprovided via storage means (e.g., RAM, ROM, a physical storage mediumsuch as a compact disc (CD) or floppy disk, etc.), such that a userterminal and/or base station can obtain the various methods uponcoupling or providing the storage means to the device. Moreover, anyother suitable technique for providing the methods and techniquesdescribed herein to a device can be utilized.

It is to be understood that the claims are not limited to the preciseconfiguration and components illustrated above. Various modifications,changes and variations may be made in the arrangement, operation anddetails of the methods and apparatus described above without departingfrom the scope of the claims.

What is claimed is:
 1. A method for wireless communications by a basestation, comprising: determining a configuration of channel stateinformation reference signals (CSI-RSs), wherein the configurationindicates a set of resource elements (REs) to be used for CSI-RSs and afirst mapping of CSI-RS ports to the set of REs, wherein theconfiguration further indicates orthogonal cover codes (OCCs) used fortransmitting the CSI-RSs, wherein the set of REs comprises one or moreRE groups, wherein a RE group of the one or more RE groups comprises twoor more localized REs within one orthogonal frequency divisionmultiplexing (OFDM) symbol, wherein the two or more localized REs areadjacent to each other in the frequency domain, and wherein the mappedCSI-RS ports are separated by the orthogonal cover codes (OCCs) appliedto the one or more RE groups in frequency domain only; sending anindication of the configuration of the CSI-RSs; and transmitting theCSI-RSs according to the determined configuration, wherein theconfiguration indicates a combination of one OFDM symbol CSI-RSs with afirst numerology having a first subcarrier spacing and two OFDM symbolsCSI-RSs with a second numerology having a second subcarrier spacing. 2.The method of claim 1, wherein: the configuration indicates that the oneOFDM symbol CSI-RSs comprises a cyclic prefix (CP) overhead, andtransmitting the CSI-RSs comprises: applying the OCCs in the timedomain, and transmitting the CSI-RSs using at least two OFDM symbolswith the second numerology having the second subcarrier spacing, whereinthe second subcarrier spacing is at least double the first subcarrierspacing and the same CP overhead.
 3. The method of claim 1, whereindetermining the configuration comprises: determining a plurality of REsto be used for a downlink transmission to a receiver; and selecting agroup of REs, which are latest in time REs of the plurality of REs, forthe set of REs to be used for the CSI-RSs.
 4. The method of claim 3,wherein data signals are not allowed to be multiplexed on the group ofthe latest REs.
 5. The method of claim 3, further comprising: receivingan acknowledgment (ACK) or a negative acknowledgment (NAK), of the datatransmitted in the downlink transmission in a slot, mini-slot, or set ofaggregated slots, in an uplink portion located in the end of the sameslot, mini-slot, or set of aggregated slots.
 6. The method according toclaim 1, wherein transmitting the CSI-RSs comprises transmitting theCSI-RSs on uniformly distributed REs in one orthogonal frequency domainmultiplexing (OFDM) symbol.
 7. The method of claim 1, whereintransmitting the CSI-RSs comprises transmitting the CSI-RSs on REshaving one frequency and uniformly distributed over time.
 8. The methodof claim 1, further comprising: signaling the configuration using atleast one of radio resource control (RRC) signaling, layer 2 (L2)signaling, or layer 1 (L1) signaling.
 9. A method for wirelesscommunications by a user equipment, comprising: receiving an indicationof a configuration of channel state information reference signals(CSI-RSs) from a transmission reception point (TRP), wherein theconfiguration indicates a set of resource elements (REs) to be used forCSI-RSs and a first mapping of CSI-RS ports to the set of REs, whereinthe configuration further indicates orthogonal cover codes (OCCs) usedfor transmitting the CSI-RSs, wherein the set of REs comprises one ormore RE groups, wherein a RE group of the one or more RE groupscomprises two or more localized REs within one orthogonal frequencydivision multiplexing (OFDM) symbol, wherein the two or more localizedREs are adjacent to each other in the frequency domain, and wherein themapped CSI-RS ports are separated by orthogonal cover codes (OCCs)applied to the one or more RE groups in frequency domain only;processing CSI-RSs based on the indicated configuration to determinechannel state information, wherein the configuration indicates acombination of one OFDM symbol CSI-RSs with a first numerology having afirst subcarrier spacing and two OFDM symbols CSI-RSs with a secondnumerology having a second subcarrier spacing; and reporting the channelstate information to the TRP.
 10. The method of claim 9, wherein theconfiguration further indicates the orthogonal cover codes (OCCs) usedfor transmitting the CSI-RSs.
 11. The method of claim 10, wherein: theconfiguration indicates the one OFDM symbol CSI-RSs comprises a cyclicprefix (CP) overhead, and processing the CSI-RSs comprises: applying theOCCs in the time domain, and receiving the CSI-RSs using at least twoOFDM symbols with the second numerology having the second subcarrierspacing, wherein the second subcarrier spacing that is at least doublethe first subcarrier spacing and the same CP overhead.
 12. The method ofclaim 9, wherein the configuration: specifies a group of REs that arelatest REs of a set of REs used for a downlink transmission to thereceiver.
 13. The method of claim 12, wherein data signals are notallowed to be multiplexed on the group of the latest REs.
 14. The methodof claim 12, further comprising: reporting an acknowledgment (ACK) or anegative acknowledgment (NAK), of the data transmitted on the downlinktransmission in a slot, mini-slot, or set of aggregated slots, in anuplink portion located in the end of the same slot, mini-slot, or set ofaggregated slots.
 15. The method according to claim 9, whereinprocessing the CSI-RSs comprises receiving the CSI-RSs on uniformlydistributed REs in one orthogonal frequency domain multiplexing (OFDM)symbol.
 16. The method of claim 9, wherein processing the CSI-RSscomprises receiving the CSI-RSs on REs having one frequency anduniformly distributed over time.
 17. The method of claim 9, furthercomprising: receiving the configuration using at least one of radioresource control (RRC) signaling, layer 2 (L2) signaling, or layer 1(L1) signaling.
 18. An apparatus for wireless communications in a basestation, comprising: a processor configured to: determine aconfiguration of channel state information reference signals (CSI-RSs),wherein the configuration indicates a set of resource elements (REs) tobe used for CSI-RSs and a first mapping of CSI-RS ports to the set ofREs, wherein the configuration further indicates the orthogonal covercodes (OCCs) used for transmitting the CSI-RSs, wherein the set of REscomprises one or more RE groups, wherein a RE group of the one or moreRE groups comprises two or more localized REs within one orthogonalfrequency division multiplexing (OFDM) symbol, wherein the two or morelocalized REs are adjacent to each other in the frequency domain, andwherein the mapped CSI-RS ports are separated by orthogonal cover codes(OCCs) applied to the one or more RE groups in frequency domain only;send an indication of the configuration of the CSI-RSs; and transmit theCSI-RSs according to the determined configuration, wherein theconfiguration indicates a combination of one OFDM symbol CSI-RSs with afirst numerology having a first subcarrier spacing and two OFDM symbolsCSI-RSs with a second numerology having a second subcarrier spacing; anda memory coupled with the processor.
 19. The apparatus of claim 18,wherein the processor is configured to transmit the CSI-RSs bytransmitting the CSI-RSs on uniformly distributed REs in one orthogonalfrequency domain multiplexing (OFDM) symbol.
 20. The apparatus of claim18, wherein the processor is configured to transmit the CSI-RSs bytransmitting the CSI-RSs on REs having one frequency and uniformlydistributed over time.
 21. An apparatus for wireless communications in auser equipment, comprising: a processor configured to: receive anindication of a configuration of channel state information referencesignals (CSI-RSs) from a transmission reception point (TRP), wherein theconfiguration indicates a set of resource elements (REs) to be used forCSI-RSs and a first mapping of CSI-RS ports to the set of REs, whereinthe configuration further indicates the orthogonal cover codes (OCCs)used for transmitting the CSI-RSs, wherein the set of REs comprises oneor more RE groups, wherein a RE group of the one or more RE groupscomprises two or more localized REs within one orthogonal frequencydivision multiplexing (OFDM) symbol, wherein the two or more localizedREs are adjacent to each other in the frequency domain, and wherein themapped CSI-RS ports are separated by orthogonal cover codes (OCCs)applied to the one or more RE groups in frequency domain only; processCSI-RSs based on the indicated configuration to determine channel stateinformation, wherein the configuration indicates a combination of oneOFDM symbol CSI-RSs with a first numerology having a first subcarrierspacing and two OFDM symbols CSI-RSs with a second numerology having asecond subcarrier spacing; and report the channel state information tothe TRP; and a memory coupled with the processor.
 22. The apparatus ofclaim 21, wherein: the configuration further indicates the orthogonalcover codes (OCCs) used for transmitting the CSI-RSs; and the processoris configured to process the CSI-RSs based on the OCCs.
 23. Theapparatus of claim 22, wherein: the configuration indicates the one OFDMsymbol CSI-RSs comprises a cyclic prefix (CP) overhead, and theprocessor is configured to process the CSI-RSs by: applying the OCCs inthe time domain, and receiving the CSI-RSs using at least two OFDMsymbols with the second numerology, wherein the second subcarrierspacing that is at least double the first subcarrier spacing and thesame CP overhead.
 24. The apparatus of claim 23, wherein: theconfiguration specifies a group of REs that are latest REs of a set ofREs used for a downlink transmission to the apparatus; and the processoris configured to process the CSI-RSs by processing the CSI-RSs in thegroup of the latest REs.
 25. The apparatus of claim 24, wherein datasignals are not allowed to be multiplexed on the group of the latestREs.
 26. The apparatus of claim 24, wherein the processor is configuredto: report an acknowledgment (ACK) or a negative acknowledgment (NAK),of the data transmitted on the downlink transmission in a slot,mini-slot, or set of aggregated slots, in an uplink portion located inthe end of the same slot, mini-slot, or set of aggregated slots.
 27. Theapparatus of claim 21, wherein the processor is configured to processthe CSI-RSs by receiving the CSI-RSs on uniformly distributed REs in oneorthogonal frequency domain multiplexing (OFDM) symbol.
 28. Theapparatus of claim 21, wherein the processor is configured to processthe CSI-RSs by receiving the CSI-RSs on REs having one frequency anduniformly distributed over time.
 29. The apparatus of claim 21, whereinthe processor is configured to: receive the configuration using at leastone of radio resource control (RRC) signaling, layer 2 (L2) signaling,or layer 1 (L1) signaling.